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Deadly Eucalyptus

Eucalyptus specialists "down under"
are larger and better equipped than North American species to forage in
flowering trees.NOTE: Bill lengths given in inchesLEFT
(top to bottom): Tasmania's Yellow Wattlebird, Australia's New Holland
Honeyeater, and Eastern Spinebill.
RIGHT (top to bottom): Yellow-rumped Warbler, Ruby-crowned Kinglet, and
Anna's Hummingbird.

Jeez! What a tree! It's late December in northern
California, but the list of birds foraging in the blossoms makes us feel
like we're in Manzanillo. In addition to many individuals of our regular
winterers - 20 Anna's Hummingbirds, 20 Audubons and 3 Orange-crowned warblers,
10 Ruby-crowned Kinglets, and a few starlings - there are two kinds of
orioles, a Palm and a Nashville warbler, a Warbling Vireo, and a Summer
Tanager! It's a Christmas Bird Count compiler's dream: six rare species,
all in one tree.

But... hmmm... something isn't natural here.

On the ground beneath the tree, we find a dead Ruby-crowned Kinglet, its
facial feathers matted flat from black, tar-like pitch. Through a hand
lens I can see that its nostrils are sealed shut. This little bird has
suffocated as a result of its attraction to an exotic plant. I wonder out
loud if the same fate becomes all the black-faced insectivores we see foraging
in flowering eucalyptus. Years ago I found a dead hummingbird with black
tar covering its bill and wondered why. It was in a cemetery in Oakland
- under eucalyptus trees.

Exotic plants

Several species of eucalyptus trees were imported to North America from
Down Under in the 1800s, for timber, windbreaks, and ornamentation. Eucalyptus
globulus, the blue gum, is native to Tasmania and has become the most common
large "euc" in California. During our winter (October to March),
many of them produce abundant flowers, which in turn attract insects that
invite these special sorts of birds. Without the presence of the trees,
many of these birds would migrate, as they should, into the American tropics.

Some exotic plants, like gorse, Scotch and French brooms, and pampas grass,
are invasive and, if allowed their own way, will displace any and all native
plants in their path. Eucalyptus do not spread as quickly, but their acrid,
aromatic leaf litter precludes an understory of other kinds of vegetation.
Except for providing occasional nest sites for Great Horned Owls and Red-shouldered
Hawks, non-blooming "eucs" do not provide much food or shelter
for native birds or other animals.

They are what they eat

Birds have evolved body types, especially bill shapes and lengths, in
accordance with their environment, their feeding strategies, and the plants
in which they forage. Honeyeaters and other species of eucalyptus specialists
indigenous to Tasmania and Australia have long, curved bills: they can
probe the flowers without involving their feathers or nostrils. Leaf-gleaners
like North American kinglets, vireos, and wood warblers, have short straight
bills. To seek insects or nectar within eucalypus blossoms, they must insert
much of their heads, thus glopping up their faces. There are no native
North American plants that invite this type of harm.

The long and ongoing arguments over eucalyptus "management" seldom
touch on wildlife issues but instead are more people-oriented. Some say
the trees have been here so long that they are naturalized citizens, or
argue how beautiful they are to the human eye. The other side calls them
unnatural or feral immigrants and fire hazards.

Native wildlife
finds little use for eucalyptus except for those trees in bloom, and many
birds that swarm to flowering "eucs" may die as a result of this
connection. Non-blooming "eucs" cause areas of ecological emptiness
that could otherwise be viable habitat if planted with native trees like
oaks or pines. From a point of view that would favor the health and prosperity
of native North American plants and animals, especially birds, eucalyptus
trees (particularly those that bloom from October to February) should be
removed.